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          489        185 
1992          764        308 
1993         1356        504 
1994         1746        640 
1995         3279       1141 
1996         3069       1084 
1997         2219        759 
1998        23060       9730 
1999        14399       5520 
2000        39935      16555 
2001        40662      15840 
2002        31853      14251 
2003        59515      24732 
2004        47176      18102 
2005        82806      25476 
2006       106595      34175 
2007       195066      60168 
2008       117006      33406 
2009        96448      27155 
2010       111084      30975 
2011       164146      45489 
2012       155329      43022 
2013       228608      65084 
2014       555280     142157 
2015       739050     194537 
2016       660447     171374 
2017       566812     153192 
2018       364085     102206 
2019       884035     215935 
2020       636830     162289 
2021       857195     204120 
2022       637088     182367 
2023       574556     164506 
2024       648290     186688 
2025        22730       6682