As the complexity of the issues facing government has increased, so too has the importance of committees to the parliament's work. After a bill reaches the Nationalrat, it is assigned to a committee and frequently also to a subcommittee. Legislators typically spent twice as much time in committee hearings as in plenary sessions. The subcommittees hold even more hours of hearings than the full committees. Because of the unwieldy nature of plenary sessions, 80 percent of changes to government legislation occur in committees.