What time ranges can Statistics show?

You can choose Today, This week, Last 4 weeks, Last 12 weeks (the default), Last 12 months, or a custom from/to range. Every KPI tile compares against the previous equivalent period; you can switch that off via "Compare with previous period" in the "..." menu. You can also narrow everything to one or more groups, and the SLA tab adds a filter for specific SLA policies. The one exception is the Topics cluster tab, which is rebuilt weekly from your whole history and is not affected by the date range.