Table 1.

The number of twin pairs that have data available on none, 1, 2, …, or all measurement occasions

	None	1	2	3	4	5	6	7	All
Twin 1	382	2131	1675	1334	491	444	242	158	41
Twin 2	374	2184	1642	1273	526	451	262	144	42

‘None’ means that only the co-twin has data available on 1 or more measurement occasions