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          468        178 
1992          740        300 
1993         1296        483 
1994         1658        609 
1995         2991       1045 
1996         2953       1044 
1997         1822        631 
1998        21585       9185 
1999        13129       5051 
2000        38409      15876 
2001        39244      15242 
2002        30769      13776 
2003        57431      23908 
2004        46077      17688 
2005        80788      24888 
2006       104238      33488 
2007       190749      59008 
2008       111073      31832 
2009        92098      25975 
2010       144217      38759 
2011       155893      43270 
2012       147353      40850 
2013       218907      62401 
2014       562501     143362 
2015       799465     210271 
2016       656106     170468 
2017       551782     149396 
2018       348926      98049 
2019       860663     210101 
2020       613035     155996 
2021       824097     195618 
2022       616568     176497 
2023       555726     158987 
2024       612308     176395 
2025       286296      82391