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         1283        478 
1994         1640        603 
1995         2906       1016 
1996         2895       1024 
1997         1790        620 
1998        21456       9130 
1999        12887       4966 
2000        38041      15712 
2001        39379      15266 
2002        32918      14462 
2003        56437      23524 
2004        45450      17462 
2005        80005      24653 
2006       103022      33129 
2007       187938      58253 
2008       106915      30716 
2009        89716      25329 
2010       141682      38104 
2011       151233      42000 
2012       142333      39487 
2013       215346      61407 
2014       548714     139703 
2015       794809     209128 
2016       646806     167962 
2017       544691     147424 
2018       339330      95407 
2019       851526     207858 
2020       594593     150902 
2021       805159     190595 
2022       609436     174449 
2023       549102     157143 
2024       605641     174102 
2025       515730     147132