Bang 10
Nam	T1	T2	T3	T4	T5	T6	T7	T8	T9	T10	T11	T12
20 12
1971	14.7	16.7	19.5	24.2	26.8	29.1	28.3	27.1	27.5	22.9	20.3	18.0
1972	16.8	16.7	20.6	22.4	27.4	29.2	28.3	27.0	27.1	25.3	21.1	17.5
1973	16.2	20.7	22.3	25.1	28.6	29.2	28.8	27.7	26.7	24.2	21.0	16.9
1974	15.9	15.7	18.0	23.3	27.8	28.8	28.8	27.9	27.8	24.6	21.7	18.4
1975	16.3	18.5	21.2	24.7	27.8	28.5	29.4	28.3	27.7	25.1	19.9	15.3
1976	16.1	18.1	19.0	22.4	26.9	28.4	29.3	27.9	27.5	24.7	18.6	18.1
1977	13.1	14.7	20.4	23.6	28.9	29.7	28.9	29.1	27.4	25.7	20.3	19.6
1978	16.2	16.7	20.5	24.0	27.0	28.5	29.1	28.6	26.4	24.3	21.0	19.3
1979	17.3	20.0	20.2	23.7	26.8	28.5	29.8	28.2	27.6	24.7	20.5	20.1
1980	17.4	15.2	22.0	23.8	27.2	28.2	28.8	28.7	27.3	25.0	23.6	18.0
1981	17.2	18.1	22.2	25.9	26.4	28.8	29.0	29.5	28.3	24.5	20.8	16.9
1982	18.1	16.6	20.2	23.2	27.0	29.3	29.4	28.6	26.9	26.0	22.7	16.0
1983	14.5	16.4	18.5	23.7	28.2	29.8	30.4	28.7	28.3	25.0	20.5	16.5
1984	13.7	14.8	19.1	23.9	26.7	28.8	29.6	28.6	27.6	23.8	22.8	17.2
1985	14.1	17.4	17.0	22.0	28.2	29.4	29.1	28.6	27.3	25.3	22.0	18.1
1986	16.7	16.2	19.9	24.4	27.0	29.0	29.1	29.0	27.3	24.3	21.3	19.3
1987	19.2	20.3	22.8	24.0	28.8	29.7	29.5	28.8	27.9	25.8	21.5	16.5
1988	17.8	16.3	17.3	22.4	28.2	29.3	29.5	28.4	28.0	24.0	20.7	18.9
1989	15.2	16.7	19.6	23.7	26.5	28.6	29.1	28.7	28.1	24.8	21.9	18.4
1990	17.3	17.6	20.0	24.4	26.1	28.9	28.7	30.2	28.2	25.1	22.6	19.6