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        34986      14969 
2003        56951      23328 
2004        44826      17074 
2005       303044     136557 
2006       330492     147583 
2007       191759      59411 
2008       107753      30743 
2009        88280      24701 
2010       135951      36212 
2011       142856      38874 
2012       170321      36935 
2013       224464      56484 
2014       471715     117057 
2015       710154     185737 
2016       599528     154934 
2017       504182     137072 
2018       301120      85161 
2019       803451     196798 
2020       527038     133545 
2021       709488     166049 
2022       551036     158058 
2023       509621     146002 
2024       549738     158016 
2025       523886     148678 
2026       371974      89124