Pulling Year Information From Text String

My client (MC) has gotten a request from one of their clients (TC) for some information stored in the DB.

The TC wants to know what years are covered by an agreement.  Should be a simple request but it complicated by the fact that for each agreement the MC has been entering this information manually into a text field.  Before explaining the requirements I fully realize that because the information is entered manually no logic will be foolproof but I have to make an attempt.

Definition:  Period – Each period should be separated by a comma in the text string.  A period can be a single year (2013) or a span of years (2010-2017).  Each span should have a “-‘ between the beginning year and the ending year.  However the spacing around the dash is inconsistent.  There can be up to 5 periods in a text string
For each period the client wants to know: Oldest Year, Newest Year and Total Number of Years in the Span.

For a period consisting of year 2013, Oldest = 2013, Newest = 2013, Number of Years = 1
For a period 2010 – 2017, Oldest = 2010, Newest = 2017, Number of years = 8

I have created logic that will determine the oldest, newest and number of years in a passed text string.  

Public Sub getMinPeriod_MaxPeriod_TotalInstallPlanPeriods(passedYearsGoverned As String, _
                                                          returnMinAgreementPeriod As Long, _
                                                          returnMaxAgreementPeriod As Long, _
                                                          returnNumberOfPeriods As Long, _
                                                          returnIs2017Included As Boolean)
                                                          
' this routine will be passed the years governed string from the install plan
' the try to pick out the min year, max year and then calculate the number of periods.
'
' basically it will create the years one by one starting at 1960.  Then it will see if that year
' exist in the string.  If it does it will make that year eithere the oldest found so far or
' the newest found so far.  At the end of looping thru the years we should have the min and max
'
Dim wkYearStr As String
Dim wkYearNum As Long
Dim wkMinPeriod As Long
Dim wkMaxperiod As Long
'
wkMinPeriod = 9999
wkMaxperiod = 0
returnIs2017Included = False
'
returnIs2017Included = False
'
For wkYearNum = 1960 To 2017
'
    wkYearStr = Trim(Str(wkYearNum))
    If InStr(1, passedYearsGoverned, wkYearStr) Then
        ' compare min
        If wkYearNum < wkMinPeriod Then
            wkMinPeriod = wkYearNum
        End If
        '  compare max
        If wkYearNum > wkMaxperiod Then
            wkMaxperiod = wkYearNum
        End If
        ' is 2017 included
        If wkYearNum = 2017 Then
            returnIs2017Included = True
        End If
        '
    End If
'
Next wkYearNum
'
' If none found them all must be returned as zero
'
If wkMinPeriod = 9999 Then
    wkMinPeriod = 0
End If
'
' calculate the number of periods
'
returnMinAgreementPeriod = wkMinPeriod
returnMaxAgreementPeriod = wkMaxperiod

returnNumberOfPeriods = wkMaxperiod - wkMinPeriod + 1
'
End Sub

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I now need to develop some logic that will parse thru the entire text string, picking off periods and sending them to my period parsing routine.  That’s where I am having difficulty.  Can anyone help?
I attached a DB including a table of all of the ‘Years Goverend’ text strings in the database.
YearInfoForEE.accdb