Table 1.

Summary of characteristics of women in the BCSC population.

Number of women		%
Age at first mammogram
40 - 44	95,768	60.0
45 - 49	31,619	19.8
50 - 54	20,689	13.0
55 - 59	11,498	7.2
Average time between screens
9 - 18 mos	31,298	39.2
19 - 30 mos	30,085	37.7
30 - 42 mos	10,252	12.8
>42 mos	8,254	10.3
Number of screening exams
1	79,684	49.9
2	33,101	20.7
3	19,139	12.0
4	11,677	7.3
5	7,318	4.6
6	4,220	2.6
7	2,417	1.5
8	1,249	0.8
9	515	0.3
10+	254	0.2