The sample described in Exercise 4.12 yields the following data on the 100 HMO enrollees selected as described above. From these data, estimate the proportion of persons in the HMO population at high risk for coronary heart disease.

Number of Record Records per CHD High Record Number of Records per CHD High Number HMO Member Risk Number HMO Member Risk 253 50 0 50253 50 0 1253 36 0 51253 47 0 2253 45 0 52253 55 0 3253 61 0 53253 56 0 4253 50 0 54253 44 0 5253 77 0 55253 36 0 62.53 70 0 56253 46 0 7253 41 0 57253 64 0 8253 63 0 58253 59 0 9253 43 0 59253 55 0 10253 53 0 60253 10 1 11253 17 I 61253 12 1 12253 44 0 62253 62 0 13253 54 0 63253 34 0 14253 70 0 64253 48 0 15253 46 0 65253 27 16253 62 0 66253 43 0 17253 48 0 67253 23 1 18253 37 0 68253 36 0 19253 53 0 69253 52 0 20253 38 0 70253 55 0 21253 39 0 71253 19 22253 53 0 72253 35 23253 25 73253 19