On a short flight from Malta NY to Philadelpha, I decided to take a quick look at the net climbing statistics from Low-Key Hillclimb years. To do this, I took the stats for each climb from the last year the climb was used (rather than the stats claimed for each given year) since on some climbs there were revisions as better data became available. I summed up the climbs for each climb for which there were finishers, omitting "X" weeks.
1995 has the most total distance and climbing since there were 12 climbs that year, including both Mt Hamilton, Mount Diablo, and Soda Springs, all long climbs. It falls fairly average on the average grade spectrum. 1998 had the least climbing despite climbing Mt Hamilton twice. The series started out short and had two climbs canceled, leaving only five.
Since we stopped doing Mount Diablo after 2009, climbing in the series has generally been less. 2013 wasn't exceptional in climbing, but distances were relatively short (2nd shortest total series in history), making average grade the highest so far by a small margin. What may be surprising is the average grade is still relatively modest at 6.48%. Flattish portions, or for that matter descending like on Mount Hamilton, provide a lot of dilution, even if the 15%+ grades which were plentiful this year provide a disproportional fraction of the pain.
Here's some numbers: