Fiddly Excel count and average calculation

I have list of data (32,000 rows deep) that looks like this:

4/1/2013 0:00      0
4/1/2013 0:01      6590
4/1/2013 0:02      0
4/1/2013 0:03      0
4/1/2013 0:04      0
4/1/2013 0:05      0
4/1/2013 0:06      0
4/1/2013 0:07      0
4/1/2013 0:08      0
4/1/2013 0:09      0
4/1/2013 0:10      0
4/1/2013 0:11      0
4/1/2013 0:12      0
4/1/2013 0:13      0
4/1/2013 0:14      0
4/1/2013 0:15      0
4/1/2013 0:16      0
4/1/2013 0:17      0
4/1/2013 0:18      0
4/1/2013 0:19      13350
4/1/2013 0:20      0
4/1/2013 0:21      0
4/1/2013 0:22      0
4/1/2013 0:23      0
4/1/2013 0:24      0
4/1/2013 0:25      0
4/1/2013 0:26      0
4/1/2013 0:27      0
4/1/2013 0:28      0
4/1/2013 0:29      0
4/1/2013 0:30      0
4/1/2013 0:31      0
4/1/2013 0:32      8640
4/1/2013 0:33      0
4/1/2013 0:34      0
4/1/2013 0:35      0
4/1/2013 0:36      0

Date & time with a flow. The Flow is usually zero.

I need to count the zeros from the first zero up to and including the next non-zero number, then divide the non-zero number and populate the adjacent column with the average flow number since the last non-zero. i.e. there are 18 zeros until 13350, 13 zeros until 8640, Like this:

4/1/2013 0:00      0      
4/1/2013 0:01      6590      
4/1/2013 0:02      0      741.6666667
4/1/2013 0:03      0      741.6666667
4/1/2013 0:04      0      741.6666667
4/1/2013 0:05      0      741.6666667
4/1/2013 0:06      0      741.6666667
4/1/2013 0:07      0      741.6666667
4/1/2013 0:08      0      741.6666667
4/1/2013 0:09      0      741.6666667
4/1/2013 0:10      0      741.6666667
4/1/2013 0:11      0      741.6666667
4/1/2013 0:12      0      741.6666667
4/1/2013 0:13      0      741.6666667
4/1/2013 0:14      0      741.6666667
4/1/2013 0:15      0      741.6666667
4/1/2013 0:16      0      741.6666667
4/1/2013 0:17      0      741.6666667
4/1/2013 0:18      0      741.6666667
4/1/2013 0:19      13350      741.6666667
4/1/2013 0:20      0      664.6153846
4/1/2013 0:21      0      664.6153846
4/1/2013 0:22      0      664.6153846
4/1/2013 0:23      0      664.6153846
4/1/2013 0:24      0      664.6153846
4/1/2013 0:25      0      664.6153846
4/1/2013 0:26      0      664.6153846
4/1/2013 0:27      0      664.6153846
4/1/2013 0:28      0      664.6153846
4/1/2013 0:29      0      664.6153846
4/1/2013 0:30      0      664.6153846
4/1/2013 0:31      0      664.6153846
4/1/2013 0:32      8640      664.6153846
4/1/2013 0:33      0      
4/1/2013 0:34      0      
4/1/2013 0:35      0      
4/1/2013 0:36      0