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          659        271 
1993         1176        442 
1994         1490        556 
1995         2374        838 
1996         2646        939 
1997         2518        860 
1998        23963       8561 
1999        12879       4909 
2000        36453      14974 
2001        41512      16305 
2002        35084      15014 
2003        57178      23418 
2004        45040      17154 
2005       303836     136879 
2006       331110     147819 
2007       192303      59554 
2008       108491      30940 
2009        89124      24927 
2010       136952      36469 
2011       144037      39189 
2012       171651      37291 
2013       226307      56990 
2014       473732     117575 
2015       714093     186778 
2016       601582     155464 
2017       507333     137965 
2018       303027      85688 
2019       806861     197723 
2020       530044     134380 
2021       714954     167478 
2022       555384     159273 
2023       511938     146661 
2024       552286     158741 
2025       526677     149437 
2026       325697      75365