Unfortunately Orion will only hold a max of 180 days of detailed stats because going longer tends to lead to oversized databases and poor performance from the web UI. Daily averages can be held for several years, but you may want to have more granularity than the average of the metric across 24 hours. I find that in cases like this you are probably best off trying to do something like using SSIS to export the daily metrics out to a warehouse that you can run your longer term reports from.
Thanks mesverrumfor your answer.
Another question: what is the interval used to calculate the StatisticData in table APM_CurrentComponentStatus for counter type 272696576? For example to get the value for Deadlocks/sec I need to take 2 samples: one for now and another one 5 minutes later then divide the difference by 300 seconds so that I know in the last 5 minutes we have X deadlocks per second. My interval is 5 minutes.