Answer: 1983 to 1989: 42.25, 43.00, 43.25, 43.75, 44.625, 45.125, 45.625
4-yearly moving totals fall between two years, so they are centred by adding consecutive pairs and dividing by 8.
| Year | Number of crimes ('000) | 4-yearly moving total | 2-period moving total (centred) | 4-yearly centred moving average (= col 4 ÷ 8) |
|---|
| 1981 | 40 | | | |
| 1982 | 42 | 167 (between 1982 and 1983) | | |
| 1983 | 43 | 171 (between 1983 and 1984) | 338 | 42.25 |
| 1984 | 42 | 173 (between 1984 and 1985) | 344 | 43.00 |
| 1985 | 44 | 173 (between 1985 and 1986) | 346 | 43.25 |
| 1986 | 44 | 177 (between 1986 and 1987) | 350 | 43.75 |
| 1987 | 43 | 180 (between 1987 and 1988) | 357 | 44.625 |
| 1988 | 46 | 181 (between 1988 and 1989) | 361 | 45.125 |
| 1989 | 47 | 184 (between 1989 and 1990) | 365 | 45.625 |
| 1990 | 45 | | | |
| 1991 | 46 | | | |
