If you apply for asylum in Greece and then illegally leave to go to another European country, according to the law you should be sent back to Greece to continue your asylum procedure there. Nevertheless, before you can be sent back, Greece has to agree to accept the request. In most of the cases, Greece is rejecting these 'take back requests'. By the end of September, European countries had sent more than 5000 'take back requests' to Greece since the beginning of 2018. Greece has so far only accepted 220 of these requests and only 13 transfers have actually been carried out. More than three quarters of the 'take back requests' were send by Germany (3874 in total).
The rejection rate for these requests is also very high, as only one in thirty requests got accepted by Greece. Norway, Sweden and Belgium have also sent between 200 to 300 'take back requests' in 2018 but only had between 11 and 29 accepted. You can find the whole statistic here. Germany and other countries are putting political pressure on Greece to achieve a higher acceptance rate for 'take back requests' in the future, so that more asylum seekers can be sent back to Greece to continue their asylum procedure. Please keep in mind, that these statistics only consider asylum seekers in Greece and not recognized refugees