I have significantly downsized my collection over the last 6 years, and the range has narrowed from where it was at its peak; but of the remaining 26, it consists of:
1920's: 5
1930's: 15
1940's: 4
1950's: 2
Well over half are Royals. My collection was probably the most balanced when I got down to around 50, but then I sort of abandoned balance and just went with favorites.