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         2625        932 
1997         2495        852 
1998        23922       8547 
1999        12835       4895 
2000        36338      14924 
2001        41428      16269 
2002        34974      14964 
2003        56913      23316 
2004        44810      17068 
2005       302979     136532 
2006       330461     147571 
2007       191715      59399 
2008       107681      30724 
2009        88190      24678 
2010       135861      36189 
2011       142763      38849 
2012       170236      36912 
2013       224284      56435 
2014       471537     117013 
2015       709768     185635 
2016       599398     154898 
2017       503873     136987 
2018       300921      85106 
2019       803088     196699 
2020       526736     133459 
2021       708888     165873 
2022       550531     157917 
2023       509385     145934 
2024       549481     157942 
2025       523703     148632 
2026       369123      88075