Well, Ed, I think catholicculture.org put a little anti-homosexual "spin" on the statistics, and the original report is careful to avoid such bias. It does appear that the victim's age is most often between 11 and 15, at the time of first offense.
You can get the original John Jay report itself at the U.S. Conference of Catholic Bishops.

Here's an excerpt:

The majority of victims are males between the ages of 11-17, and just over half (50.7%) of all individuals who made allegations of abuse were between the ages of 11-14. The average age of all alleged victims is 12.6. This number has increased over time, however. In the 1950s, the average age was 11.5; in the 1960s it was 12; in the 1970s it was 12.87; in the 1980s it was 13.2; and by the 1990s it was 13.87.



Table 4.3.1 GENDER OF ALLEGED VICTIM

Gender	Count	% of Total
Male	8,499	80.9%
Female	2,004	19.1%
Transsexual	2	0.0%
Total	10,505	100.0%





Table 4.3.2 VICTIM'S AGE AT FIRST INSTANCE OF ABUSE

Age in Years	Count	% of Total
1	4	0.0%
2	11	0.1%
3	22	0.2%
4	41	0.5%
5	82	1.0%
6	158	1.8%
7	220	2.5%
8	369	4.1%
9	362	4.0%
10	752	8.4%
11	895	10.0%
12	1,323	14.7%
13	1,141	12.8%
14	1,188	13.2%
15	1,042	11.6%
16	769	8.6%
17	577	6.5%
Total	8,956	100%