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         2891       1011 
1996         2889       1022 
1997         1784        618 
1998        21444       9124 
1999        12857       4955 
2000        37895      15649 
2001        39069      15146 
2002        34827      15094 
2003        56662      23568 
2004        45114      17339 
2005        79668      24549 
2006       102530      32980 
2007       186752      57935 
2008       104940      30182 
2009        88336      24964 
2010       140760      37862 
2011       148913      41365 
2012       139628      38750 
2013       213470      60884 
2014       541559     137810 
2015       796117     209556 
2016       636729     164735 
2017       542722     146956 
2018       335406      94339 
2019       847796     207203 
2020       586476     148633 
2021       797016     188427 
2022       604316     173003 
2023       544744     155890 
2024       601518     172844 
2025       573579     163979