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         1484        554 
1995         2353        831 
1996         2620        930 
1997         2492        851 
1998        23916       8544 
1999        12827       4892 
2000        36313      14912 
2001        41414      16263 
2002        34959      14957 
2003        56882      23305 
2004        44788      17059 
2005       302866     136489 
2006       330384     147545 
2007       191649      59382 
2008       107556      30691 
2009        88102      24656 
2010       135746      36161 
2011       142622      38810 
2012       170122      36881 
2013       224100      56380 
2014       471236     116935 
2015       709279     185502 
2016       599146     154829 
2017       503494     136877 
2018       300717      85048 
2019       802602     196573 
2020       526032     133293 
2021       708148     165672 
2022       549949     157751 
2023       509008     145826 
2024       549190     157859 
2025       522243     148423 
2026       367103      87426