Some breeds are known for being generally more broody or less broody. Sometimes, it just depends on the strain or genetics of a particular breed. You can breed broodiness into or out of a line of chickens, just like any other quality.
Most of my chickens over the years have tended to not go broody. A few years ago I got a few chickens (of a breed I'd already had) from a particular source and they have been much broodier. None of them went broody as pullets. They were the broodiest their first spring as hens, when they were just a year old. They were all broody at least once that year. At least one was broody 2 or 3 times. In the following years, only half usually go broody and it's only once a year. Thank goodness! Some people have occasionally posted about pullets going broody, but I've never had that happen. I don't know what's most common.
Some of your pullets may decide to go broody next year, when they're a little older. Maybe when spring hits, your new hens will have settled in and be inspired by the longer days, lush grass and warm days. I hope you get all the broodies you want or need. Hens and their chicks are so adorable.