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          444        170 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2894       1012 
1996         2889       1022 
1997         1784        618 
1998        21444       9124 
1999        12857       4955 
2000        37897      15650 
2001        39069      15146 
2002        34827      15094 
2003        56665      23569 
2004        45114      17339 
2005        79670      24550 
2006       102534      32981 
2007       186779      57942 
2008       104976      30192 
2009        88353      24969 
2010       140784      37868 
2011       148952      41375 
2012       139690      38766 
2013       213505      60894 
2014       541724     137854 
2015       795928     209509 
2016       636873     164775 
2017       542304     146841 
2018       335505      94368 
2019       847789     207195 
2020       586620     148676 
2021       797158     188470 
2022       604399     173028 
2023       544839     155917 
2024       601770     172911 
2025       574384     164216