Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          656        270 
1993         1176        442 
1994         1487        555 
1995         2356        832 
1996         2628        933 
1997         2498        853 
1998        23922       8547 
1999        12837       4896 
2000        36342      14926 
2001        41431      16270 
2002        34981      14967 
2003        56931      23322 
2004        44824      17073 
2005       303026     136551 
2006       330484     147580 
2007       191736      59405 
2008       107712      30732 
2009        88244      24692 
2010       135911      36202 
2011       142831      38867 
2012       170268      36920 
2013       224385      56462 
2014       471588     117026 
2015       709979     185692 
2016       599473     154920 
2017       504036     137032 
2018       301028      85135 
2019       803295     196753 
2020       526900     133506 
2021       709190     165960 
2022       550795     157991 
2023       509508     145970 
2024       549614     157980 
2025       523801     148654 
2026       369562      88299