Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          503        190 
1992          936        367 
1993         1669        610 
1994         2326        839 
1995         3580       1242 
1996         3576       1256 
1997         2335        796 
1998        23272       9812 
1999        14535       5574 
2000        40496      16805 
2001        43079      16705 
2002        32544      14548 
2003        61323      25421 
2004        48049      18429 
2005        85616      26320 
2006       111037      35477 
2007       204590      62725 
2008       125711      35769 
2009       102278      28739 
2010       118865      33006 
2011       178321      49314 
2012       165607      45788 
2013       256708      72685 
2014       643143     163233 
2015       747099     197154 
2016       573155     152723 
2017       610764     163639 
2018       403835     112541 
2019       941740     230564 
2020       691328     177264 
2021       898389     215147 
2022       667155     190837 
2023       606313     174567 
2024       200922      57840