During my pros residency and implant fellowship in general we saw a 93-95% success rate. There are many factors that affect success. This is a great article:

Int J Oral Maxillofac Implants. 2005 Jul-Aug;20(4):569-77.

Dental implant failure rates and associated risk factors.
Moy PK, Medina D, Shetty V, Aghaloo TL.

Oral and Maxillofacial Surgery, University of California at Los Angeles, School of Dentistry, Los Angeles, California, USA.

PURPOSE: To guide treatment planning by analyzing the rates of dental implant failure to determine associated risk factors. MATERIALS AND METHODS: All consecutively treated patients from January 1982 until January 2003 were included in a retrospective cohort study, as defined in the hierarchy of evidence for dental implant literature. Data regarding gender, age, implant location, bone quality, bone volume, and medical history were recorded. Correlations between these data and implant survival were calculated to establish relative risk (RR) ratios. RESULTS: Increasing age was strongly associated with the risk of implant failure. Compared to patients younger than 40 years, patients in the 60-to-79 age group had a significantly higher risk of implant failure (RR = 2.24; P < .05). Gender, hypertension, coronary artery disease, pulmonary disease, steroid therapy, chemotherapy, and not being on hormone replacement therapy for postmenopausal women were not associated with a significant increase in implant failure. Smoking (RR = 1.56), diabetes (RR = 2.75), head and neck radiation (RR = 2.73), and postmenopausal estrogen therapy (RR = 2.55) were correlated with a significantly increased failure rate. Overall, implant failure was 8.16% in the maxilla and 4.93% in the mandible (P < .001). DISCUSSION: Patients who were over age 60, smoked, had a history of diabetes or head and neck radiation, or were postmenopausal and on hormone replacement therapy experienced significantly increased implant failure compared with healthy patients. CONCLUSION: Overall, dental implant failure is low and there are no absolute contraindications to implant placement. Conditions that were found to be correlated with an increased risk of failure should be considered during treatment planning and factored into the informed consent process.

I think it varies from practice to practice. In my hands its about 94%. I think the long term studies where on machined surface implants, we dont have any lond term studies on implants with the different surfaces that are out today.

I would say that in general its 90-95%